Organic devices such as OLED-devices contain at least one active organic layer on a substrate sandwiched between two electrodes. To protect the active organic layer and other functional parts of the device, a cap is bonded to the substrate with the help of a bonding material. Usually the cap is bonded to the substrate using polymeric adhesives, for example epoxy adhesives, as bonding material. The bonding material fixes the cap on the substrate and acts as a barrier to harmful atmospheric gases such as oxygen and moisture. After mounting the cap on the substrate, the adhesive has to be cured. Many commonly used adhesives can be cured by heat treatment, for example on a hot plate or in an oven. However, heat treatment can damage the active organic layer or other functional parts of the device and can therefore adversely affect the performance of the device. To avoid damaging of the device during the heat treatment, the curing temperatures are generally adjusted to the temperature tolerance of the active organic layer or other functional parts of the device and not only to the curing properties of the bonding material. On the one hand, this can lead to enhanced permeation rates for harmful atmospheric gases of the cured bonding material and on the other hand, limits the number of bonding materials suited for sealing the device. Particularly, higher curing temperatures can allow the use of bonding materials with lower permeation rates for gases like oxygen and moisture.
In U.S. Pat. No. 6,692,610, a method of fabricating devices such as OLED-devices is disclosed. The method includes applying an adhesive on a cap or substrate. The adhesive is partially cured to initiate the cross-linking process while remaining in the liquid phase. The cap is then mounted onto the substrate and the adhesive is cured to encapsulate the device. By partially curing the adhesive prior to mounting the cap, the curing of the adhesive can be achieved without prolonged exposure to UV-radiation or high temperatures, which can adversely impact the device.
However, this method requires a further process step which makes the production of devices more complicated and expensive. Furthermore, the above-mentioned U.S. Pat. No. 6,692,610 does not disclose an alternative to the heat treatment, which would allow the use of bonding material with improved barrier properties.